In the medical delivery field, beneficial agents are packaged in flexible containers such as I.V. bags and are ultimately delivered through tubing such as an administration set to patients to achieve therapeutic effects. Port tubing is a necessary feature of the container and provides access to the contents of the container. I.V. bags are most commonly fabricated from polymers such as polyvinyl chloride, ethylene vinyl acetate, or polyolefin alloys, such as those disclosed in co-pending and commonly assigned U.S. patent Ser. No. 08/153,823. The I.V. containers usually have two confronting walls or panels that are attached to one another along a peripheral seam to make a fluid tight compartment.
Conventional containers employ port designs from one of two broad categories, panel ports and edge ports. Panel ports are attached to the container on a panel and are often centrally disposed. The panel port extends perpendicularly from the face of the panel. Edge ports are attached between the two panels along a peripheral seam of the container and extend parallel to the panels.
Panel ports are easily installed but have a number of drawbacks. First, panel ports, by design, necessitate the use of one or more injection molded parts. These injection molded parts are costly, especially at lower production volumes. Containers having panel ports also have the undesired tendency to retain a residual volume of fluid due to incomplete drainage.
Edge ports have a different set of design issues. Edge ports are prone to a defect known as "channel leak." Channel leak occurs along the port tube and results from an incomplete seal between the planar surfaces of the panels and the rounded surface of the port tube. Channel leak is more likely to occur when the container is fabricated from material that has a high modulus, and especially when using thin layers of such a stiff material, as the material will have a tendency to crease upon folding.
Prior attempts at overcoming the channel leak problems have led to the use of injection molded parts. These parts are commonly used in containers constructed from biaxially oriented nylon, foil, TEFLON.RTM., polyester, and multilayer structures containing these polymers or inelastic materials. The injection molded parts are inserted between the panels and, in most instances, have a tapered outer profile. The purpose of the taper is to provide fillet material to the area where channel leak is likely to occur. Again, these injection molded parts are quite expensive, especially in low volume production.
U.S. Pat. No. 4,023,607 discloses a polyethylene urine bag having a polyethylene tubing inserted therein to provide access to the interior of the bag. The tubing is attached between two polyethylene film sheets that constitute the side walls of the bag. A heat sealing technique is used to seal the tube to the side walls. Shaped dies, as shown in FIG. 2 of the '607 Patent, are used in the heat sealing step. The tubing is "somewhat compressed" in the direction of the motion of the sealing dies during the heat sealing process. The '607 Patent does not fully compress the tubing to a flattened state and therefore requires attaching the container sidewalls to a rounded member. Such a procedure may lead to channel leak because it is difficult to form a good weld between planar members and rounded members.
The present invention is provided to solve these and other problems.